Other types of leveling devices are known to the art but none of these devices disclose the unique features of the present inventions.
For example, Schering U.S. Pat. No. 4,470,198 is somewhat similar to the present inventions but the feet of the apparatus are blunt rather than sharp. Also, because the abutments are points in Schering, the Schering device would have limited applications for making measurements other than those shown in the Schering patent. Schering does show a level sensing device 8 that is off to the side and senses the position of the tool. Topping U.S. Pat. No. 4,506,448 shows a position sensing device with three probes including one spring mounted probe. The entire device is mounted at the end of the arm of a robot to determine the position of the arm with respect to some fixed part. It cannot be said that it contained an angle sensing unit. Frissora U.S. Pat. No. 4,480,390 shows a device having two side legs to be placed on a roll, but the remainder of the mechanism is quite different from the present invention even though it is intended to measure position. Emmerich U.S. Pat. No. 4,123,848 shows a device which has two legs that touch a roll, but the rest of the device consists of a number of plastic sheets which have scales on them which are lined up with the tool by eye and accordingly are quite different from the present invention. Gettel U.S. Pat. No. 3,252,223 is likewise a purely mechanical device in which various parts are held in position by sensors. Johnson U.S. Pat. No. 2,777,210 shows a system for measuring the position of a tool with respect to a rotating body on a lathe, but the principle of operation is completely different from the present invention. North U.S. Pat. No. 4,467,527 shows a digital level but is mounted in a rectangular body. The patent has more to do with the structure in a circular digital level than with the type of measurements carried out by the present invention. Face U.S. Pat. No. 4,434,558 shows a measuring device which has points at the two sides both of which are solidly mounted but one is adjustable. The center point is fixed. A gauge 22 measures the tilt and displays a digital reading. The concept in Face is very different and one skilled in the art would not expect to use this device for the principle purposes for the present invention. In general the tool of the present invention has uses for measuring characteristics that would be difficult or impossible to measure using the tools in the prior art.